In a multi-beam system, a terminal device and a network device may train multiple beams by beam forming, and different beams may correspond to different directions and different coverage areas. Specifically, the terminal device may have multiple uplink transmitting beams and multiple downlink receiving beams, and the network device may have multiple uplink receiving beams and multiple downlink transmitting beams. Before performing the specific uplink data transmission, the terminal device and the network device need to separately determine the uplink transmitting beams and the uplink receiving beams used in the current data transmission, and before performing the specific downlink data transmission, the terminal device and the network device need to separately determine the downlink transmitting beams and the downlink receiving beams used in the current downlink data transmission, which cause large signaling overhead and heavy burden on equipment.